This application is based on and claims priority under 35 U.S.C. xc2xa7 119 with respect to German Application No. P 100 32 590.4 filed on Jul. 7, 2000, the entire content of which is incorporated herein by reference.
The present invention generally relates to bearing units. More particularly, the present invention pertains to a lockable bearing unit and a method for locking a bearing unit.
A known bearing unit is disclosed in German Auslegeschrift No. 1 904 954. This document discloses a journal-free rotary connection provided with a braking device configured as a disk brake.
A need exists for a device usable in conjunction with machine parts that are rotatable relative to one another, by which the rotary movement can be optionally disabled or enabled.
A need also exists for a method by which the rotatable movement of machine parts is capable of being permitted (enabled) and prevented (disabled) as desired.
The present invention provides a mechanism used in conjunction with machine parts that are rotatable relative to one another to optionally enable and disable the relative rotational movement of the machine parts led or enabled. The invention also involves a method for disabling and enabling such rotary movement.
In the bearing unit according to the present invention, the relative rotary or rotational movement between first and second bearing rings is disabled by virtue of a locking device that is integrated into the bearing unit to interconnect the first and the second bearing rings in a form-fit manner. This locking device can be remote controlled.
The form-fit connection, in contrast to a friction brake, has the advantage that precise locking against rotation is reliably guaranteed even at very high torques. A further advantage is that relatively little power is required to create or cancel the operation of the lock. As a result, little difficulties arise with respect to dissipating heat. In addition, the design is relatively compact and so the invention can be used even in bearings with small geometric dimensions. Also, it is possible to substantially eliminate brake linings which are subject to wear and thus cause additional maintenance costs.
Integrating the locking device into the bearing unit also provides the advantage that the bearing unit can be locked exclusively by components contained in or integrated into the bearing unit. Thus, other than the necessary control connection, external machine parts are generally not required. That is, the bearing unit according to the present invention can be mounted like a conventional bearing and does not require any significantly special installation environment. Care should be taken in generally ensuring that the bearing rings are mounted so as to be secure against rotation.
The bearing unit according to the present invention has the further advantage that the form-fit connection between the first and second bearing rings can be produced in many different ways. This allows the conditions of a specific application to be optimally taken into account. For instance, a relatively precise lock between the inner and outer raceways by mutually engaging gear teeth is just as possible as an inexpensive and highly compact lock produced by way of a pin/bore combination.
The bearing unit according to the present invention also has a wide range of application and generally universal use in that it can be configured for all the usual control methods such as pneumatic control, hydraulic control, mechanical control, electrical or magnetic control.
According to an aspect of the present invention, a bearing unit includes a first bearing ring mounted about a shaft and a second bearing ring mounted about the shaft, with the first and second bearing rings being relatively rotatable with respect to one another. A locking device selectively locks the first bearing ring relative to the second bearing ring, and includes a piston in the bearing unit urged in one direction by a biasing force to produce an unlocked state of the locking device in which relative rotational movement between the first bearing ring and the second bearing ring is permitted, and movable in opposition to the biasing force to produce a locked state of the locking device in which the first bearing ring and the second bearing ring are interconnected to prevent relative rotational movement of the first bearing ring and the second bearing ring. A control device is operatively connected to the piston to move the piston in opposition to the biasing force to produce the locked state of the locking device.
In accordance with another aspect of the invention, a method for locking a bearing unit that includes first and second bearing rings that are relatively rotatable involves interconnecting the first bearing ring and the second bearing ring in a form-fit manner to lock the bearing unit by a locking device that is integrated in the bearing unit, with the form-fit interconnection being canceled to cancel the lock of the bearing unit. The form-fit interconnection of the first bearing ring and the second bearing ring is established and canceled by remote control.